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Discussion Starter #1
Okay. I'll try to explain this as clear as possible.

My cold air return is basically a joist cavity for half the run and then the other half is duct work tied in to the joist cavity. The cold air return vent is on the first floor and that ties into the joist cavity in the basement.


I would like to know if its possible to make a small hole in one of the joist to run coax cable up about 18 inches to the first floor?


I read somewhere that as long as the cable is not running along the entire length of the return it is okay. It must also be perpendicular and plenum rated.

Any truth to this?
 

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I read somewhere that as long as the cable is not running along the entire length of the return it is okay. It must also be perpendicular and plenum rated.

Any truth to this?

It must be perpendicular and plenum rated


Correct.
 

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Discussion Starter #5
So you can run perpendicular if its a joist cavity and not metal ductwork right?


Also, what would be considered a plenum in a residential house?
 

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Lic Elect/Inspector/CPO
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It can be run perpendicular to the plenum without it being plenum rated. If you run the length of the plenun than it has to be plenum rated.
 

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Master Electrician
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So you can run perpendicular if its a joist cavity and not metal ductwork right?


Also, what would be considered a plenum in a residential house?
The top of the furnace where the duct work branches from is the plenum.
 

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:oops:I just noticed you are talking about COAX!

Do what you want and have fun!


Thanks for the clarification on the plenum rating guys!:thumbsup:
 

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Discussion Starter #9
So what brric said about NM-B wire can also apply to coax right?

I just want to be absolutely sure.

Thanks.
 

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Licensed Electrician
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There ARE codes in the NEC for CATV installation. It is not a "free-for-all" as some seem to think.
 

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820.113 Installation of Coaxial Cables. Installation of co-
axial cables shall comply with 820.113(A) through (K).
Installation of raceways shall comply with 820.110.

(A) Listing. Coaxial cables installed in buildings shall be
listed.
Exception: Coaxial cables that comply with 820.48 shall not
be required to be listed.
(B) Fabricated Ducts Used for Environmental Air. The
following cables shall be permitted in ducts as described in
300.22(B) if they are directly associated with the air distri-
bution system:
(1) Up to 1.22 m (4 ft) of Type CATVP cable (the P means plenum listed)

(C) Other Spaces Used For Environmental Air (Plenums).
The following cables shall be permitted in other spaces used
for environmental air as described in 300.22(C):
(1) Type CATVP cable
(2) Type CATVP cable installed in plenum communica-
tions raceway
(3) Type CATVP cable supported by open metallic cable
trays or cable tray systems
(4) Types CATVP, CATVR, CATV, and CATVX cables in-
stalled in raceways that are installed in compliance
with 300.22(C)

300.22 Wiring in Ducts Not Used for Air Handling,
Fabricated Ducts for Environmental Air, and Other
Spaces for Environmental Air (Plenums).

C) Other Spaces Used for Environmental Air (Ple-
nums). This section shall apply to spaces not specifically
fabricated for environmental air-handling purposes but used
for air-handling purposes as a plenum. This section shall
not apply to habitable rooms or areas of buildings, the
prime purpose of which is not air handling.


Exception: This section shall not apply to the joist or stud
spaces of dwelling units where the wiring passes through
such spaces perpendicular to the long dimension of such
spaces.



The way I am reading this, the perpendicular exception also applies to CATV cable.

Thanks for the homework!

I am taking the NEC class next semester, and am trying to get a head start.
 
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Just found this, it sure helps!


 

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DIY Enthusiast
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820.113 Installation of Coaxial Cables. Installation of co-
axial cables shall comply with 820.113(A) through (K).
Installation of raceways shall comply with 820.110.

(A) Listing. Coaxial cables installed in buildings shall be
listed.
Exception: Coaxial cables that comply with 820.48 shall not
be required to be listed.
(B) Fabricated Ducts Used for Environmental Air. The
following cables shall be permitted in ducts as described in
300.22(B) if they are directly associated with the air distri-
bution system:
(1) Up to 1.22 m (4 ft) of Type CATVP cable (the P means plenum listed)

(C) Other Spaces Used For Environmental Air (Plenums).
The following cables shall be permitted in other spaces used
for environmental air as described in 300.22(C):
(1) Type CATVP cable
(2) Type CATVP cable installed in plenum communica-
tions raceway
(3) Type CATVP cable supported by open metallic cable
trays or cable tray systems
(4) Types CATVP, CATVR, CATV, and CATVX cables in-
stalled in raceways that are installed in compliance
with 300.22(C)

300.22 Wiring in Ducts Not Used for Air Handling,
Fabricated Ducts for Environmental Air, and Other
Spaces for Environmental Air (Plenums).

C) Other Spaces Used for Environmental Air (Ple-
nums). This section shall apply to spaces not specifically
fabricated for environmental air-handling purposes but used
for air-handling purposes as a plenum. This section shall
not apply to habitable rooms or areas of buildings, the
prime purpose of which is not air handling.

Exception: This section shall not apply to the joist or stud
spaces of dwelling units where the wiring passes through
such spaces perpendicular to the long dimension of such
spaces.

The way I am reading this, the perpendicular exception also applies to CATV cable.
So it seems it is a "free for all" in this situation.
How about that!
 

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Super Moderator
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13,963 Posts
It is not a free for all. The cable needs to follow the rules shown above.

Sublime, many here try to only give answers that follow the code. When you give answers it would help greatly if you would give correct answers also not just ones you agree with.
 

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DIY Enthusiast
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1,131 Posts
It is not a free for all. The cable needs to follow the rules shown above.

Sublime, many here try to only give answers that follow the code. When you give answers it would help greatly if you would give correct answers also not just ones you agree with.
As I said,IN THIS SITUATION with this particular person it is a free for all as kbuz put it. The code is posted above for all to see what is required in DIFFERENT situations.
Thanks for the advice though!
 

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Licensed Electrician
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4,352 Posts
From how I interpret the OPs situation, he would need plenium rated cat 5, because it is not running thru the joists.

Not to mention the possible violations for cutting a jack into a stud space being used as a cold air return.
 

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A stud cavity used for a furnace air return is a plenum. It has access to a continuous supply of air that will support combustion of flammable materials such as cables. But it does not have to be lined with sheet metal. Contrasted with a normal stud cavity that is closed on all sides and ends.
 

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Discussion Starter #19 (Edited)
What if I made a tiny hole, just big enough to fit the coax and make sure it is plenum rated? Would that be okay?

I made a crude picture for clarification





Based on the picture, you might be thinking why I didn't just go straight up to the low voltage plate. There is a pipe in the way underneath. So I wanted to avoid hitting it if possible.
 

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Yes you can run plenum rated cable CATVP any way you want but are limited to 4 feet max inside the plenum.

Would either blue line work? Both OK with plain CATV.
 
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